Conditional Build Tag for Partially words on Topic Title

Yes you can apply a CBT to part of a topic title provided the topic title is not being automatically generated (e.g. through a Master Page). The problem here is that the TOC and topic title are two different things. When you add a topic to a TOC, it automatically adds a TOC entry using the topic title as it currently exists. If you need to change this, you have to do this manually. It can not update to Overview or Introduction according to how you use CBTs.

You maybe able to handle this with a TOC variable though depending on the version of RoboHelp you are using. You still need to apply the CBT to the topic title, but also create a variable set (over and above the default one) with one variable. For each of the two variable sets, set the variable value to "Overview" and "Introduction". Then in the CHM single source layout specify the appropriate variable set. If you wanted to be very clever you could have two CHM single source layouts each with the different variable sets and use the Batch Generate facility to generate both outputs.

Let us know which version of RH you are using if you need further help.